The present application relates to medical devices for delivery of pharmaceutically active materials. More specifically, the present invention relates to methods and compositions effective to prevent reduction in the activity of pharmaceutically active materials arising from contact with metallic components of medical devices.
Medical devices having metallic components are used extensively in the medical field. In many cases the medical device is used for delivery of a pharmaceutically active material, and the pharmaceutically active material comes into contact with the metallic component during the course of delivery of the pharmaceutically active material. For example, metallic lumens are frequently used to carry pharmaceutically active materials to various bodily tissues. As another example, metallic stents having a drug delivery polymer coating thereon are used for delivery of pharmaceutically active materials. In both examples, the pharmaceutically active material contacts the metallic component. Metallic components such as stainless steel and nickel-titanium superelastic alloys (e.g., nitinol), cobalt based alloys and super-alloys are commonly used for this purpose as they are formable, have desirable mechanical properties and are commonly believed to be substantially inert.
The present inventors, however, have found that such materials are incompatible with certain pharmaceutically active materials. As a result, there is at present a need in the art to overcome this incompatibility.